Chemical control systems and methods for controlling disinfectants

ABSTRACT

A method of automatically controlling chloramine concentration in a body of water contained in a reservoir includes: (a) determining residual chloramine concentration in a water sample obtained from the body of water; (b) determining at least one of the following when the residual chloramine concentration is below a predetermined target chloramine concentration level: (i) an average rate of change in total chlorine concentration; and (ii) an average rate of change in oxidation-reduction potential; and (c) automatically engaging a supply of ammonia and a supply of chlorine to add both ammonia and chlorine to the body of water at a weight ratio of chlorine to ammonia of 5:1 or less when the average rate of change in total chlorine concentration is below a set rate of change and/or the average rate of change in oxidation-reduction potential is above a set rate of change.

The subject application claims the benefit of provisional applicationSer. No. 62/560,252 filed Sep. 19, 2017, which is incorporated herein byreference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to chemical control systems forcontrolling disinfectants, such as chloramines, and methods of operatingsuch systems.

Description of Related Art

Water utilities typically add disinfectants to water systems to preventcontamination from germs and bacteria. The most commonly used secondarydisinfectant is chlorine; however, while chlorine is a strongdisinfectant, it has a short residual life and readily formsdisinfection byproducts such as trihalomethanes. In order to avoid thedrawbacks associated with chlorine, many water utilities are turning tochloramines as an alternative. As compared to chlorine, chloramines havea longer residual life and are less prone to disinfection byproductformation. Despite these advantages, chloramine usage can beproblematic. For instance, a water system is typically dosed withhypochlorite and ammonia to produce monochloramine; however, if thechlorine-to-ammonia ratio is not accurately controlled, undesirableside-effects occur such as nitrification, over-chlorination, and lowoxidation levels. Thus, it is desirable to provide a chemical injectionsystem that can be accurately controlled to continuously produce stableforms of monochloramine in a water system at a desired concentration.

SUMMARY OF THE INVENTION

Generally, provided is an improved chloramine injection and controlsystem and method.

In one preferred and non-limiting embodiment or aspect, provided is amethod of automatically controlling chloramine concentration in a bodyof water contained in a reservoir. The method includes: (a) determiningresidual chloramine concentration in a water sample obtained from thebody of water; (b) determining at least one of the following when theresidual chloramine concentration is below a predetermined targetchloramine concentration level: (i) an average rate of change in totalchlorine concentration based on residual total chlorine concentrationsof water samples obtained from the body of water; and (ii) an averagerate of change in oxidation-reduction potential based onoxidation-reduction potentials of water samples obtained from the bodyof water; and (c) automatically engaging a supply of ammonia and asupply of chlorine to add both ammonia and chlorine to the body of waterat a weight ratio of chlorine to ammonia of 5:1 or less when: (i) theaverage rate of change in total chlorine concentration is below a setrate of change in total chlorine concentration; (ii) the average rate ofchange in oxidation-reduction potential is above a set rate of change inoxidation-reduction potential; or (iii) the average rate of change intotal chlorine concentration is below a set rate of change in totalchlorine concentration and the average rate of change inoxidation-reduction potential is above a set rate of change inoxidation-reduction potential.

In some preferred and non-limiting embodiments or aspects, the averagerate of change in total chlorine concentration is determined in step(b), and ammonia and chlorine are both added to the body of water at aweight ratio of chlorine to ammonia of 5:1 or less in step (c) when (i)the average rate of change in total chlorine concentration is below theset rate of change in total chlorine concentration. In another preferredand non-limiting embodiment or aspect, the average rate of change inoxidation-reduction potential is determined in step (b), and ammonia andchlorine are both added to the body of water at a weight ratio ofchlorine to ammonia of 5:1 or less in step (c) when (ii) the averagerate of change in oxidation-reduction potential is above the set rate ofchange in oxidation-reduction potential. In yet another preferred andnon-limiting embodiment or aspect, the average rate of change in totalchlorine concentration and the average rate of change inoxidation-reduction potential is determined in step (b), and ammonia andchlorine are both added to the body of water at a weight ratio ofchlorine to ammonia of 5:1 or less in step (c) when (iii) the averagerate of change in total chlorine concentration is below the set rate ofchange in total chlorine concentration and the average rate of change inoxidation-reduction potential is above the set rate of change inoxidation-reduction potential.

In some preferred and non-limiting embodiments or aspects, the methodfurther includes automatically engaging a supply of chlorine to addchlorine only to the body of water if the residual chloramineconcentration in the water sample obtained from the body of water instep a) is below the predetermined target chloramine concentrationlevel. In another preferred and non-limiting embodiment or aspect, themethod further includes automatically engaging a supply of chlorine anda supply of ammonia to add both chlorine and ammonia to the body ofwater at a weight ratio of chlorine to ammonia of greater than 5:1 ifthe residual chloramine concentration in the water sample obtained fromthe body of water in step a) is below the predetermined targetchloramine concentration level.

In certain preferred and non-limiting embodiments or aspects, a feedrate of the chlorine and ammonia supplied to the body of water afterstep a) is different than a feed rate of the chlorine and ammoniasupplied to the body of water in step c).

In some preferred and non-limiting embodiments or aspects, the averagerate of change in total chlorine concentration and the average rate ofchange in oxidation-reduction potential in step (b) is determined whenthe supply of chlorine is disengaged. Further, the average rate ofchange in total chlorine concentration is determined by measuring thechange in residual total chlorine concentration in consecutivelyobtained water samples over a fixed period of time, and the average rateof change in oxidation-reduction potential is determined by measuringthe change in oxidation-reduction potential in consecutively obtainedwater samples over a fixed period of time.

In some preferred and non-limiting embodiments or aspects, if theaverage rate of change in total chlorine concentration is determined tobe at or above the set rate of change in total chlorine concentration,chlorine only is added to the body of water. Further, in anotherpreferred and non-limiting embodiment or aspect, if the average rate ofchange in oxidation-reduction potential is determined to be at or belowthe set rate of change in oxidation-reduction potential, chlorine onlyis added to the body of water.

Moreover, the supply of chlorine and the supply of ammonia are added tothe body of water during step (c) until a subsequently obtained watersample is determined to be at or above the predetermined targetchloramine concentration level.

In some preferred and non-limiting embodiments or aspects, thepredetermined target chloramine concentration level comprises a minimumpredetermined total chlorine concentration set-point and a maximumpredetermined total chlorine concentration set-point. Further, the feedrate of the chlorine and/or the ammonia is decreased when the totalchlorine concentration is at or above the minimum predetermined totalchlorine concentration set-point and below the maximum predeterminedtotal chlorine concentration set-point. In addition, the supply ofchlorine and the supply of ammonia are disengaged when the totalchlorine concentration is at or above the maximum predetermined totalchlorine concentration set-point.

In certain preferred and non-limiting embodiments or aspects, the feedrate of the chlorine and ammonia are determined by reservoir watervolume and dwell time. Further, the residual chloramine concentrationcan be based on a residual total chlorine concentration and thepredetermined target chloramine concentration level can be based on atarget total chlorine concentration level. The oxidation-reductionpotentials of the samples can be determined by measuring millivolts ofthe water samples.

The present invention is also directed to a treatment delivery systemfor automatically controlling chloramine concentration in a body ofwater contained in a reservoir. The system includes: a chemical dosingassembly; a water sampling assembly configured to extract water samplefrom the body of water at different points in time; one or moreanalyzers in fluid communication with the water sampling assembly andconfigured to determine at least residual total chlorine concentrationand optionally oxidation-reduction potential in the water samples; acontroller in operable communication with the analyzers; and one or morecomputer-readable storage mediums in operable communication with thecontroller and containing programming instructions that, when executed,cause the controller to: (a) determine residual chloramine concentrationin a water sample obtained from the body of water; (b) determine atleast one of the following when the residual chloramine concentration isbelow a predetermined target chloramine concentration level: (i) anaverage rate of change in total chlorine concentration based on residualtotal chlorine concentrations of water samples obtained from the body ofwater; and (ii) an average rate of change in oxidation-reductionpotential based on oxidation-reduction potentials of water samplesobtained from the body of water; and (c) automatically engage a supplyof ammonia and a supply of chlorine to add both ammonia and chlorine tothe body of water at a weight ratio of chlorine to ammonia of 5:1 orless when: (i) the average rate of change in total chlorineconcentration is below a set rate of change in total chlorineconcentration while chlorine is added to the body of water; (ii) theaverage rate of change in oxidation-reduction potential is above a setrate of change in oxidation-reduction potential while chlorine is addedto the body of water; or (iii) the average rate of change in totalchlorine concentration is below a set rate of change in total chlorineconcentration and the average rate of change in oxidation-reductionpotential is above a set rate of change in oxidation-reductionpotential.

In some preferred and non-limiting embodiments or aspects, the chemicaldosing assembly is at least partially submerged in the body of water.Further, in certain preferred and non-limiting embodiments or aspects,the computer-readable storage mediums in operable communication with thecontroller further comprise programming instructions that, whenexecuted, cause the controller to automatically engage a supply ofchlorine to add chlorine only to the body of water if the residualchloramine concentration in the water sample obtained from the body ofwater in step a) is below the predetermined target chloramineconcentration level. In another preferred and non-limiting embodiment oraspect, the computer-readable storage mediums in operable communicationwith the controller further comprise programming instructions that, whenexecuted, cause the controller to automatically engage a supply ofchlorine and a supply of ammonia to add both chlorine and ammonia to thebody of water at a weight ratio of chlorine to ammonia of greater than5:1 if the residual chloramine concentration in the water sampleobtained from the body of water in step a) is below the predeterminedtarget chloramine concentration level.

Additional preferred and non-limiting embodiments or aspects are setforth and described in the following clauses.

Clause 1: A method of automatically controlling chloramine concentrationin a body of water contained in a reservoir, the method comprising: a)determining residual chloramine concentration in a water sample obtainedfrom the body of water; b) determining at least one of the followingwhen the residual chloramine concentration is below a predeterminedtarget chloramine concentration level: i) an average rate of change intotal chlorine concentration based on total chlorine concentrations ofwater samples obtained from the body of water; and ii) an average rateof change in oxidation-reduction potential based on oxidation-reductionpotentials of water samples obtained from the body of water; and c)automatically engaging a supply of ammonia and a supply of chlorine toadd both ammonia and chlorine to the body of water at a weight ratio ofchlorine to ammonia of 5:1 or less when: i) the average rate of changein total chlorine concentration is below a set rate of change in totalchlorine concentration; ii) the average rate of change inoxidation-reduction potential is above a set rate of change inoxidation-reduction potential; or iii) the average rate of change intotal chlorine concentration is below a set rate of change in totalchlorine concentration and the average rate of change inoxidation-reduction potential is above a set rate of change inoxidation-reduction potential.

Clause 2: The method of clause 1, wherein the average rate of change intotal chlorine concentration is determined in step b), and whereinammonia and chlorine are both added to the body of water at a weightratio of chlorine to ammonia of 5:1 or less in step c) when i) theaverage rate of change in total chlorine concentration is below the setrate of change in total chlorine concentration.

Clause 3: The method of clause 1, wherein the average rate of change inoxidation-reduction potential is determined in step b), and whereinammonia and chlorine are both added to the body of water at a weightratio of chlorine to ammonia of 5:1 or less in step c) when ii) theaverage rate of change in oxidation-reduction potential is above the setrate of change in oxidation-reduction potential.

Clause 4: The method of any of clause 1, wherein the average rate ofchange in total chlorine concentration and the average rate of change inoxidation-reduction potential is determined in step b), and whereinammonia and chlorine are both added to the body of water at a weightratio of chlorine to ammonia of 5:1 or less in step c) when iii) theaverage rate of change in total chlorine concentration is below the setrate of change in total chlorine concentration and the average rate ofchange in oxidation-reduction potential is above the set rate of changein oxidation-reduction potential.

Clause 5: The method of any of clauses 1 to 4, further comprisingautomatically engaging a supply of chlorine to add chlorine only to thebody of water if the residual chloramine concentration in the watersample obtained from the body of water in step a) is below thepredetermined target chloramine concentration level.

Clause 6: The method of any of clauses 1 to 4, further comprisingautomatically engaging a supply of chlorine and a supply of ammonia toadd both chlorine and ammonia to the body of water at a weight ratio ofchlorine to ammonia of greater than 5:1 if the residual chloramineconcentration in the water sample obtained from the body of water instep a) is below the predetermined target chloramine concentrationlevel.

Clause 7: The method of clause 6, wherein a feed rate of the chlorineand ammonia supplied to the body of water after step a) is differentthan a feed rate of the chlorine and ammonia supplied to the body ofwater in step c).

Clause 8: The method of clause 1 or 4, wherein the average rate ofchange in total chlorine concentration and the average rate of change inoxidation-reduction potential in step b) is determined when the supplyof chlorine and ammonia are disengaged.

Clause 9: The method of any of clauses 1 to 8, wherein the average rateof change in total chlorine concentration is determined by measuring thechange in residual total chlorine concentration in consecutivelyobtained water samples over a fixed period of time, and wherein theaverage rate of change in oxidation-reduction potential is determined bymeasuring the change in oxidation-reduction potential in consecutivelyobtained water samples over a fixed period of time.

Clause 10: The method of any of clauses 1 to 9, wherein, if the averagerate of change in total chlorine concentration is determined to be at orabove the set rate of change in total chlorine concentration, chlorineonly is added to the body of water or chlorine and ammonia are added tothe body of water at a weight ratio of chlorine to ammonia of greaterthan 5:1.

Clause 11: The method of any of clauses 1 to 9, wherein, if the averagerate of change in oxidation-reduction potential is determined to be ator below the set rate of change in oxidation-reduction potential,chlorine only is added to the body of water or chlorine and ammonia areadded to the body of water at a weight ratio of chlorine to ammonia ofgreater than 5:1.

Clause 12: The method of any of clauses 1 to 11, wherein the supply ofchlorine and the supply of ammonia are added to the body of water duringstep c) until a subsequently obtained water sample is determined to beat or above the predetermined target chloramine concentration level.

Clause 13: The method of any of clauses 1 to 12, wherein thepredetermined target chloramine concentration level comprises a minimumpredetermined total chlorine concentration set-point and a maximumpredetermined total chlorine concentration set-point, and wherein thefeed rate of the chlorine and/or the ammonia is decreased when the totalchlorine concentration is at or above the minimum predetermined totalchlorine concentration set-point and below the maximum predeterminedtotal chlorine concentration set-point, and wherein the supply ofchlorine and the supply of ammonia are disengaged when the totalchlorine concentration is at or above the maximum predetermined totalchlorine concentration set-point.

Clause 14: The method of any of clauses 1 to 13, wherein the feed rateof the chlorine and ammonia are determined by reservoir water volume anddwell time.

Clause 15: The method of any of clauses 1 to 14, wherein the residualchloramine concentration is based on a residual total chlorineconcentration and the predetermined target chloramine concentrationlevel is based on a target total chlorine concentration level.

Clause 16: The method of any of clauses 1 to 15, wherein theoxidation-reduction potentials of the samples are determined bymeasuring millivolts of the water samples.

Clause 17: A treatment delivery system for automatically controllingchloramine concentration in a body of water contained in a reservoircomprising: a chemical dosing assembly; a water sampling assemblyconfigured to extract a water sample from the body of water at differentpoints in time; one or more analyzers in fluid communication with thewater sampling assembly and configured to determine at least totalchlorine concentration, and optionally, oxidation-reduction potential inthe water samples; a controller in operable communication with the oneor more analyzers; and one or more computer-readable storage mediums inoperable communication with the controller and containing programminginstructions that, when executed, cause the controller to: a) determineresidual chloramine concentration in a water sample obtained from thebody of water; b) determine at least one of the following when theresidual chloramine concentration is below a predetermined targetchloramine concentration level: i) an average rate of change in totalchlorine concentration based on residual total chlorine concentrationsof water samples obtained from the body of water; and ii) an averagerate of change in oxidation-reduction potential based onoxidation-reduction potentials of water samples obtained from the bodyof water; and c) automatically engage a supply of ammonia and a supplyof chlorine to add both ammonia and chlorine to the body of water at aweight ratio of chlorine to ammonia of 5:1 or less when: i) the averagerate of change in total chlorine concentration is below a set rate ofchange in total chlorine concentration while chlorine is added to thebody of water; ii) the average rate of change in oxidation-reductionpotential is above a set rate of change in oxidation-reduction potentialwhile chlorine is added to the body of water; or iii) the average rateof change in total chlorine concentration is below a set rate of changein total chlorine concentration and the average rate of change inoxidation-reduction potential is above a set rate of change inoxidation-reduction potential.

Clause 18: The system of clause 17, wherein the chemical dosing assemblyis at least partially submerged in the body of water.

Clause 19: The system of any clauses 17 or 18, wherein thecomputer-readable storage mediums in operable communication with thecontroller further comprise programming instructions that, whenexecuted, cause the controller to automatically engage a supply ofchlorine to add chlorine only to the body of water if the residualchloramine concentration in the water sample obtained from the body ofwater in step a) is below the predetermined target chloramineconcentration level.

Clause 20: The system of clauses 17 or 18, wherein the computer-readablestorage mediums in operable communication with the controller furthercomprise programming instructions that, when executed, cause thecontroller to automatically engage a supply of chlorine and a supply ofammonia to add both chlorine and ammonia to the body of water at aweight ratio of chlorine to ammonia of greater than 5:1 if the residualchloramine concentration in the water sample obtained from the body ofwater in step a) is below the predetermined target chloramineconcentration level.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a treatment delivery system according to theprinciples of the present invention;

FIG. 2 illustrates a chemical dosing assembly according to theprinciples of the present invention;

FIG. 3 is a chloramine breakpoint curve;

FIG. 4 depicts graphs illustrating the addition of chlorine in thepresence of free ammonia to generate chloramine;

FIG. 5 depicts graphs illustrating the addition of chlorine and ammoniain the absence of free ammonia to generate chloramine;

FIG. 6 is a graph of the residual chloramine concentration and additionof chlorine and ammonia using a process according to the principles ofthe present invention; and

FIG. 7 is a graph of the total chlorine, oxidation-reduction potential,rate of change of total chlorine concentration, rate of change ofoxidation-reduction potential, and the feed rate of chlorine and ammoniausing a process according to the principles of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

For purposes of the following detailed description, it is to beunderstood that the invention may assume various alternative variationsand step sequences, except where expressly specified to the contrary.Moreover, other than in any operating examples, or where otherwiseindicated, all numbers expressing, for example, quantities ofingredients used in the specification and claims are to be understood asbeing modified in all instances by the term “about”. Accordingly, unlessindicated to the contrary, the numerical parameters set forth in thefollowing specification and attached claims are approximations that mayvary depending upon the desired properties to be obtained by the presentinvention. At the very least, and not as an attempt to limit theapplication of the doctrine of equivalents to the scope of the claims,each numerical parameter should at least be construed in light of thenumber of reported significant digits and by applying ordinary roundingtechniques.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contains certainerrors necessarily resulting from the standard variation found in theirrespective testing measurements.

Also, it should be understood that any numerical range recited herein isintended to include all sub-ranges subsumed therein. For example, arange of “1 to 10” is intended to include all sub-ranges between (andincluding) the recited minimum value of 1 and the recited maximum valueof 10, that is, having a minimum value equal to or greater than 1 and amaximum value of equal to or less than 10.

Further, the terms “upper,” “lower,” “right,” “left,” “vertical,”“horizontal,” “top,” “bottom,” “lateral,” “longitudinal,” andderivatives thereof shall relate to the invention as it is oriented inthe drawing figures. However, it is to be understood that the inventionmay assume alternative variations and step sequences, except whereexpressly specified to the contrary. It is also to be understood thatthe specific devices and processes illustrated in the attached drawings,and described in the specification, are simply exemplary embodiments ofthe invention. Hence, specific dimensions and other physicalcharacteristics related to the embodiments disclosed herein are not tobe considered as limiting.

In this application, the use of the singular includes the plural andplural encompasses singular, unless specifically stated otherwise. Inaddition, in this application, the use of “or” means “and/or” unlessspecifically stated otherwise, even though “and/or” may be explicitlyused in certain instances.

Referring to FIG. 1, and in one preferred and non-limiting embodiment oraspect, the present invention is directed to a treatment delivery system10 that can be used to automatically control chloramine concentration ina body of water 12 contained in a reservoir 14. The term “automaticcontrol” refers to the absence of substantial participation of a humanoperator in normal operations manually controlling the controllablecomponents. As such, the treatment delivery system 10 can be controlledwithout an operator monitoring or adjusting the various parameters ofthe treatment delivery system 10 during normal operations.

As shown in FIG. 1, the treatment delivery system 10 can include achemical dosing assembly 16 that can be at least partially submerged inthe body of water 12. Referring to FIG. 2, and in one preferred andnon-limiting embodiment or aspect, the chemical dosing assembly 16 caninclude a water motive tube 20, a first chemical treatment flow tube 22,and optionally, a second chemical treatment flow tube 24. The watermotive tube 20 and chemical treatment flow tubes 22, 24 of the chemicaldosing assembly 16 can be oriented to expel water and chemicals,respectively, into the body of water 12 held in the reservoir 14. Thechemicals used with the chemical treatment tubes 22, 24 can be selectedto form chloramine, such as monochloramine, when expelled into a jet ofwater expelled from the water motive tube 20. For example, the firstchemical treatment flow tube 22 can be in fluid communication with asource of chlorine and can be configured to expel chlorine into the bodyof water 12 while the second chemical treatment flow tube 24 can be influid communication with a source of ammonia and can be configured toexpel ammonia into the body of water 12. Because of the configuration ofthe nozzle ends of the first and second chemical treatment flow tubes22, 24, the chemicals expelled through the ends thereof come into almostimmediate contact with one another and can begin reacting soon afterbeing expelled into the body of water 12.

In addition, and in one preferred and non-limiting embodiment or aspect,the water motive tube 20 is positioned below the release point of thefirst and second chemical treatment flow tubes 22, 24 to circulate thechemicals into the body of water 12. The flow of water out of the watermotive tube 20 can also create a high energy, high velocity mixing zonedirectly above the water motive tube 20 where the chemicals can bereleased, which helps the chemicals interact and form a particularcompound, such as monochloramine. The treatment delivery system 10 caninclude multiple chemical dosing assemblies 16 strategically locatedthroughout the reservoir 14.

The treatment delivery system 10 can further include a water samplingassembly 26 that is configured to obtain or extract water samples fromthe body of water 12 at different points in time, such as continuously,periodically, and/or according to a pre-programmed cycle. As shown inFIG. 2, the water sampling line 26 can be a component of the chemicaldosing assembly 16. For example, the water motive tube 20, chemicaltreatment tubes 22, 24, and water sampling assembly 26 of the chemicaldosing assembly 16 can be secured to a frame 27 that is adapted to restat the bottom of the reservoir 14. Alternatively, the water motive tube20, the chemical treatment tubes 22, 24, and the water sampling assembly26 can extend into the reservoir 14 to a desired depth. Yet anotheralternative (not shown) is that the water sampling assembly 26 can beseparate from the chemical dosing assembly 16 and may be located at anylocation within the reservoir 14. Treatment delivery system 10 may alsoinclude multiple water sampling assemblies 26 positioned throughout thereservoir 14. It is appreciated that the water sample can also beobtained from other methods including, but not limited to, watersampling with a submersible pump positioned inside the reservoir 14.

Referring to FIG. 1, and in one preferred and non-limiting embodiment oraspect, the treatment delivery system 10 can also include one or moreanalyzers 30 that are in fluid communication with the water samplingassembly 26. The analyzer(s) 30 are configured to receive the watersamples and analyze the contents thereof in order to determine thechloramine concentration. Various methods are known to determine thechloramine concentration in a sample of water. In one preferred andnon-limiting embodiment or aspect, the analyzer(s) 30 are programmed orconfigured to determine the concentration of total chlorine of the watersample, the oxidation-reduction potential of the water sample, or boththe concentration of total chlorine and the oxidation-reductionpotential of the water sample. The present invention can also includeanalyzer(s) 30 programmed to determine other parameters including, butnot limited to, pH, temperature, and combinations thereof. It will beappreciated that the analyzer(s) 30 may be a standalone device or, inother embodiments, may be software and/or firmware executed by thecontroller 40 or other processor.

In one preferred and non-limiting embodiment or aspect, the analyzer 30is, or includes, a total chlorine analyzer, such as the total chlorineanalyzer commercially available from ProMinent Fluid Controls, Inc. ofPittsburgh, Pa., which can be used to indirectly measure the chloramineconcentration. The analyzer(s) 30 can also be configured to measureoxidation-reduction potential which reflects the ability of certainchemical components in the water to accept or lose electrons. It isappreciated that the total chlorine residual and/or oxidation-reductionpotential measurements in a water sample are used to determine theresidual chloramine concentration either by the analyzer 30 or by acontroller 40 or other processor associated therewith. In some preferredand non-limiting embodiment or aspect, the analyzer(s) 30 is, or alsoincludes, a chloramine analyzer, such as the APA 6000 Ammonia andMonochloramine Analyzer commercially available from Hach Company ofLoveland, Colo., which can directly measure the chloramine concentrationin the water sample.

As indicated, the treatment delivery system 10 can further include acontroller 40 that is in operable communication with the analyzer(s) 30so that measurements and other data gathered, and/or determined by theanalyzer(s) 30, can be transferred or accessed by the controller 40. Oneor more computer-readable storage mediums can be in operablecommunication with the controller 40. The computer-readable storagemediums can contain programming instructions that, when executed, causethe controller 40 to perform multiple tasks. This includes programmingalgorithms such as those described herein that allow the controller 40to control the administration of chlorine and/or ammonia into the bodyof water 12 for establishing, reestablishing, and maintaining targetresidual chloramine levels within the body of water 12. The programminginstructions can be updated and modified. For example, the targetresidual chloramine level can be changed as can the flow rates of thechlorine and/or ammonia and the water sampling frequency.

In one example, and in one preferred and non-limiting embodiment oraspect, the programming instructions, when executed, can cause thecontroller 40 to: measure and/or analyze a water sample obtained fromthe body of water 12, and/or determine whether the residual chloramineconcentration in the water sample is below a predetermined residualchloramine concentration set-point or below a chloramine concentrationpercentage of a predetermined residual chloramine concentrationset-point (both which are also referred to herein as a “predeterminedchloramine concentration target level”); when the residual chloramineconcentration is below a predetermined target chloramine concentrationlevel, determine an average rate of change in total chlorineconcentration based on residual total chlorine concentrations of watersamples obtained from the body of water and/or an average rate of changein oxidation-reduction potential based on oxidation-reduction potentialsof water samples obtained from the body of water; and automaticallyengage a supply of ammonia and a supply of chlorine to add both ammoniaand chlorine to the body of water at a weight ratio of chlorine toammonia of 5:1 or less when: the average rate of change in totalchlorine concentration is below a set rate of change in total chlorineconcentration; the average rate of change in oxidation-reductionpotential is above a set rate of change in oxidation-reductionpotential; or the average rate of change in total chlorine concentrationis below a set rate of change in total chlorine concentration and theaverage rate of change in oxidation-reduction potential is above a setrate of change in oxidation-reduction potential. It is appreciated thatcontroller 40 may include one or more microprocessors, CPUs, and/orother computing devices.

As further shown in FIG. 1, and in one preferred and non-limitingembodiment or aspect, treatment delivery system 10 can include multiplechemical storage tanks, such as a first chemical storage tank 200 and asecond chemical storage tank 300, which are configured to transportchemicals to the chemical dosing assembly 16 via one or more meteringpumps. As indicated, the treatment delivery system 10 can deliver asource of chlorine and a source of ammonia into the body of water 12. Assuch, the chemical storage tanks 200, 300 can store a source of chlorineand a source of ammonia. Because the treatment delivery system 10 iscapable of delivering any type of chlorine and ammonia source, thechemical storage tanks 200, 300 can be selected to store various sourcesof chlorine and ammonia. Non-limiting examples of chlorine sources thatcan be used with the present invention include pressurized chlorine gasand hypochlorites such as sodium hypochlorite, potassium hypochlorite,and calcium hypochlorite. Non-limiting examples of ammonia sources thatcan be used with the present invention include pressurized anhydrousammonia, aqueous ammonia, and liquid ammonium sulfate. The chemicalstorage tanks 200, 300 can also be supplied by on-site chemicalgeneration systems, such as an on-site hypochlorite generation system400 as shown in FIG. 1 for example that can generate hypochlorite basedchemicals (e.g., sodium hypochlorite or potassium hypochlorite) directlyat the water treatment site.

Non-limiting examples of chemical dosing assemblies, chemical generationsystems, and the like are disclosed in U.S. Pat. No. 9,039,902, which isincorporated by reference herein in its entirety. In particular, U.S.Pat. No. 9,039,902 describes chemical dosing assemblies, as well as ahypochlorite generation system, that can be used as the source ofchlorine that is present in first chemical storage tank 200 and,ultimately, supplied to the body of water 12. The treatment deliverysystem 10 can also utilize other mixing systems as well. For example,the treatment delivery system 10 can also utilize the mixing systemdisclosed in U.S. Pat. No. 7,862,302, which is incorporated by referenceherein in its entirety.

As indicated, the present invention is also directed to a method ofautomatically controlling chloramine concentration in a body of water 12contained in a reservoir 14. The method can be implemented through oneor more algorithms and controls contained in programming instructionsthat, when executed, cause the system 10 to take certain actions, asdescribed below.

The method can first include measuring, analyzing, and/or determiningthe residual chloramine concentration in a water sample obtained fromthe body of water 12. The water sample can be obtained with the watersampling assembly 26 and transported to the analyzer 30 that is in fluidcommunication with the water sampling assembly 26. The analyzer 30 canthen measure, analyze, and/or determine the residual chloramineconcentration. The determination of the residual chloramineconcentration can include measuring the residual total chlorineconcentration in the water sample.

The residual chloramine concentration determination can be reported to acontroller 40 that is in operable communication with one or morecomputer-readable storage mediums. The controller 40 also has knowledgeof, or access to, information about the predetermined chloramineconcentration target level, which can be based on a residual totalchlorine concentration target level, for example. In some preferred andnon-limiting embodiments or aspects, if the residual chloramineconcentration in the water sample is determined to be below thepredetermined chloramine concentration target level (which can be basedon a residual total chlorine concentration set-point, for example),additional water samples are obtained from the body of water 12 todetermine the average rate of change in total chlorine concentrationbased on residual total chlorine concentrations of the water samplesand/or an average rate of change in oxidation-reduction potential basedon oxidation-reduction potentials of the water samples.

As used herein, the “average rate of change in the total chlorineconcentration” refers to the change in the total chlorine concentrationvalue over time based on the total chlorine concentration in two or morewater samples. Further, the “average rate of change in theoxidation-reduction potential” refers to the change in theoxidation-reduction potential value over time based on theoxidation-reduction potential in two or more water samples.

In some preferred and non-limiting embodiments or aspects, the averagerate of change in total chlorine concentration and/oroxidation-reduction potential is determined by comparing the totalchlorine concentration and/or oxidation-reduction potential in aplurality of water samples obtained after a fixed period of time. Forexample, the average rate of change in total chlorine concentrationand/or oxidation-reduction potential can be based on the average changein total chlorine concentration and/or oxidation-reduction potentialbetween consecutively obtained water samples over a specified period oftime, such as 10 minutes or 30 minutes or one hour for example.

The rate of change in the total chlorine concentration oroxidation-reduction potential is determined by the least squaresregression. Non-limiting examples of such equations are described inSlope Filtering: An FIR Approach to Linear Regression, IEEE SIGNALPROCESSING MAGAZINE, November 2008, pages 159 to 163. The rate of changein the total chlorine concentration or oxidation-reduction potential canalso be determined by the following formula: average rate of change=lastdetermined total chlorine concentration value or oxidation-reductionpotential value−first determined total chlorine concentration value oroxidation-reduction potential value/time the water sample of the lastdetermined value was obtained−time the water sample of the firstdetermined value was obtained. Thus, the programming instructions caninclude the average rate of change formula to allow the controller 40 todetermine the average rate of change in total chlorine concentrationand/or oxidation-reduction potential in the body of water 12.

After determining the average rate of change in total chlorineconcentration and/or oxidation-reduction potential, ammonia and chlorineare both added to the body of water 12 at a weight ratio of chlorine toammonia of 5:1 or less if: the average rate of change in total chlorineconcentration is below a set rate of change in chloramine concentration;the average rate of change in oxidation-reduction potential is above aset rate of change in oxidation-reduction potential; or the average rateof change in total chlorine concentration is below a set rate of changein total chlorine concentration and the average rate of change inoxidation-reduction potential is above a set rate of change inoxidation-reduction potential when the supply of chlorine is disengagedor while chlorine is added to the body of water 12. The chlorine andammonia can be added to the body of water 12 as previously describedthrough treatment tubes 22 and 24 of the chemical dosing assembly 16.

As used herein, a “set rate of change in total chlorine concentration”refers to a predetermined (target) increase or decrease in the rate ofchange in total chlorine concentration, and a “set rate of change inoxidation-reduction potential” refers to a predetermined (target)increase or decrease in the rate of change in oxidation-reductionpotential. For example, the set rate of change in total chlorineconcentration can be 0.05 mg/L/hour and if the average rate of change inresidual total chlorine concentration is determined to be below 0.05mg/L/hour, the programming instructions will cause the controller 40 toautomatically engage (or control) a supply of chlorine and ammonia toadd both ammonia and chlorine to the body of water 12 at a weight ratioof chlorine to ammonia of 5:1 or less. In another non-limiting example,the method of the present invention includes a set rate of change inoxidation-reduction potential such as 40 mV/hour and if the average rateof change in oxidation-reduction potential is determined to be above 40mV/hour, the programming instructions will cause the controller 40 toautomatically engage (or control) a supply of chlorine and ammonia toadd both ammonia and chlorine to the body of water 12 at a weight ratioof chlorine to ammonia of 5:1 or less.

In yet another non-limiting example, the method of the present inventionincludes a set rate of change in total chlorine concentration such as0.05 mg/L/hour and a set rate of change in oxidation-reduction potentialsuch as 40 mV/hour. If the average rate of change in residual totalchlorine concentration is determined to be below 0.05 mg/L/hourdetermined and the average rate of change in oxidation-reductionpotential is determined to be above 40 mV/hour, the programminginstructions will cause the controller 40 to automatically engage (orcontrol) a supply of chlorine and ammonia to add both ammonia andchlorine to the body of water 12 at a weight ratio of chlorine toammonia of 5:1 or less.

It is appreciated that the set rate of change in total chlorineconcentration and/or oxidation-reduction potential can be based on apositive or negative rate of change. For instance, the set rate ofchange in total chlorine concentration can be a positive rate of changeand the set rate of change in oxidation-reduction potential can be anegative rate of change. As used herein, a “positive rate of change”refers to an increase in the total chlorine concentration and/oroxidation-reduction potential over a period of time, and a “negativerate of change” refers to a decrease in the total chlorine concentrationand/or oxidation-reduction potential over a period of time.

In some preferred and non-limiting embodiments or aspects, the methodstep of adding both chlorine and ammonia into the body of water 12 at aweight ratio of chlorine to ammonia of 5:1 or less is controlled by oneof the following algorithms: (1) w<y=add both chlorine and ammonia at aweight ratio of chlorine to ammonia of 5:1 or less, where “w” is therate of change in total chlorine concentration determined from the watersamples and “y” is the set rate of change in total chlorineconcentration; (2) o>p=add both chlorine and ammonia at a weight ratioof chlorine to ammonia of 5:1 or less, where “o” is the rate of changein oxidation-reduction potential determined from the water samples and“p” is the set rate of change in oxidation-reduction potential; and/or(3) w<y and o>p=add both chlorine and ammonia at a weight ratio ofchlorine to ammonia of 5:1 or less, where “w” is the rate of change intotal chlorine concentration determined from the water samples, “y” isthe set rate of change in total chlorine concentration, “o” is the rateof change in oxidation-reduction potential determined from the watersamples, and “p” is the set rate of change in oxidation-reductionpotential. Thus, the programming instructions can include at least one,or all, of the previous algorithms that, when satisfied, will cause thecontroller 40 to automatically engage (or control) a supply of chlorineand a supply of ammonia to add both chlorine and ammonia to the body ofwater 12 at a weight ratio of chlorine to ammonia of 5:1 or less.

Chlorine and ammonia are added to the body of water 12 until asubsequently obtained water sample is determined to be at or above thepredetermined chloramine concentration target level, at which point theprogramming instructions will cause the controller 40 to stop the supplyof chlorine and the supply of ammonia into the body of water 12.

In some preferred and non-limiting embodiments or aspects, thepreviously described method step of stopping the addition of chlorineand ammonia into the body of water 12 is controlled by the followingalgorithm in which the predetermined chloramine concentration targetlevel is a residual chloramine concentration set-point based on a singlevalue: z≥x=stop the supply of chlorine and ammonia, where “z” is theresidual chloramine concentration determined in a subsequent watersample as chlorine and ammonia are being supplied to the body of water12, and “x” is a residual chloramine concentration set-point. Thus, theprogramming instructions can include algorithm that, when satisfied,will cause the controller 40 to stop automatically engaging (orcontrolling) a supply of chlorine and a supply of ammonia, andtherefore, stop adding chlorine and ammonia to the body of water 12.

In some preferred and non-limiting embodiments or aspects, thecontroller 40 is programmed to stop the supply of chlorine and ammoniainto the body of water 12 when the residual chloramine concentration isabove a particular percentage of the residual chloramine concentrationset-point. For example, the controller 40 can be programmed to stop thesupply of chlorine and ammonia into the body of water 12 when theresidual chloramine concentration in a water sample is a percentageselected within a range of 101% to 110% of the residual chloramineconcentration set-point, or a percentage selected within a range of 101%to 105% of the residual chloramine concentration set-point.

In such preferred and non-limiting embodiments or aspects, differentprogramming algorithms are used to control when the supply of chlorineand ammonia into the body of water 12 are stopped. For instance, themethod step of stopping the supply of chlorine can be controlled by thefollowing algorithm: z>[(t)(x)]=stop the supply of chlorine and ammonia,where “z” is the residual chloramine concentration determined in asubsequent water sample as chlorine and ammonia are being supplied tothe body of water 12, “t” is a percentage selected within a range of101% to 110%, and “x” is the residual chloramine concentrationset-point. Thus, the programming instructions can include, or can bemodified to include, the above algorithm that, when satisfied, willcause the controller 40 to stop automatically engaging (or controlling)a supply of chlorine and a supply of ammonia.

In some preferred and non-limiting embodiments or aspects, thepredetermined chloramine concentration target level for controlling andstopping the supply of chlorine and ammonia can include a minimumpredetermined chloramine concentration set-point and a maximumpredetermined chloramine concentration set-point. The programminginstructions will cause the controller 40 to perform certain functionswhen the chloramine concentration is at or above the minimumpredetermined chloramine concentration set-point but below the maximumpredetermined chloramine concentration set-point, and to performdifferent functions when the chloramine concentration is at or above themaximum predetermined chloramine concentration set-point. For instance,the predetermined chloramine concentration target level for controllingand stopping the supply of chlorine and ammonia can comprise: (i) aminimum predetermined chloramine concentration set-point that causes thecontroller 40 to decrease the feed rate of the chlorine and/or theammonia into the body of water 12; and (ii) a maximum predeterminedchloramine concentration set-point that causes the controller 40 to stopthe supply of chlorine and/or the ammonia into the body of water 12.

In some preferred and non-limiting embodiments or aspects, the methodstep of controlling and stopping the addition of chlorine and ammoniainto the body of water 12 is controlled by the following algorithms: z≥xand z≤y=decrease the feed rate of the supply of chlorine and ammonia;and z≥y=stop the supply of chlorine and ammonia, where “z” is theresidual chloramine concentration determined in a subsequent watersample as chlorine and ammonia are being supplied to the body of water12, “x” is a minimum predetermined chloramine concentration set-point,and “y” is a maximum predetermined chloramine concentration set-point.Thus, the programming instructions can include the above algorithmsthat, when satisfied, will cause the controller 40 to control and/orstop automatically engaging (or controlling) a supply of chlorine and asupply of ammonia, and therefore, modify and/or stop adding chlorine andammonia to the body of water 12.

As previously mentioned, the predetermined chloramine concentrationtarget level for controlling and stopping the supply of chlorine andammonia can be based on a total chlorine concentration target level.Thus, it is appreciated that the predetermined chloramine concentrationtarget level used in the previously described method steps andalgorithms for controlling and stopping the supply of chlorine andammonia can be based on a predetermined total chlorine concentrationset-point, a percentage of the predetermined total chlorineconcentration set-point, or a minimum predetermined total chlorineconcentration set-point and a maximum predetermined total chlorineconcentration set-point. In such embodiments, the residual chloramineconcentration is based on and/or determined from the residual totalchlorine concentration in the water samples.

As indicated, the supply of chlorine can be engaged and added to thebody of water 12 prior to determining the rate of change in totalchlorine concentration and/or oxidation-reduction potential. Forinstance, in some preferred and non-limiting embodiments or aspects,chlorine, and optionally, ammonia are supplied to the body of water 12after determining that the residual chloramine concentration in thewater sample is below the predetermined chloramine concentration targetlevel and before determining the average rate of change in totalchlorine concentration and/or oxidation-reduction potential. In somepreferred and non-limiting embodiments or aspects, the previouslydescribed method step of adding chlorine into the body of water 12before determining the rate of change in total chlorine concentrationand/or oxidation-reduction potential is controlled by the followingalgorithm: z<x=add chlorine, where “z” is the residual chloramineconcentration determined in the water sample and “x” is the residualchloramine concentration set-point. Thus, the programming instructionscan include the above algorithm that, when satisfied, will cause thecontroller 40 to automatically engage (or control) a supply of chlorineto add chlorine to the body of water 12.

As previously described, the chlorine and ammonia can both be suppliedto the body of water 12 after determining that the residual chloramineconcentration in the water sample is below the predetermined chloramineconcentration target level and before determining the average rate ofchange in total chlorine concentration and/or oxidation-reductionpotential. In such embodiments, the chlorine and ammonia are supplied tothe body of water 12 at a weight ratio of chlorine to ammonia of greaterthan 5:1. In some preferred and non-limiting embodiments or aspects, thepreviously described method step of adding chlorine and ammonia into thebody of water 12 before determining the rate of change in total chlorineconcentration and/or oxidation-reduction potential is controlled by thefollowing algorithm: z<x=add chlorine and ammonia at a weight ratio ofchlorine to ammonia of greater than 5:1, where “z” is the residualchloramine concentration determined in the water sample and “x” is theresidual chloramine concentration set-point. Thus, the programminginstructions can include the above algorithm that, when satisfied, willcause the controller 40 to automatically engage (or control) a supply ofchlorine and ammonia to add chlorine and ammonia to the body of water 12at a weight ratio of chlorine to ammonia of greater than 5:1.

Further, in such embodiments where chlorine and ammonia are supplied tothe body of water 12 at a weight ratio of chlorine to ammonia of greaterthan 5:1, the weight ratio of chlorine to ammonia is adjusted to 5:1 orless when the set rate of change in total chlorine concentration and/orthe set rate of change in oxidation-reduction potential are notsatisfied as previously described. Further, the feed rate of ammonia andchlorine supplied at a weight ratio of chlorine to ammonia of greaterthan 5:1 can be the same or different than the feed rate of ammonia andchlorine supplied at a weight ratio of chlorine to ammonia of greaterthan 5:1. For example, the feed rate of ammonia and chlorine supplied ata weight ratio of chlorine to ammonia of greater than 5:1 can be thegreater or lower than the feed rate of ammonia and chlorine supplied ata weight ratio of chlorine to ammonia of greater than 5:1.

In certain preferred and non-limiting embodiments or aspects, the methoduses a chloramine concentration percentage to determine when to engage(or control) and add a supply of chlorine, and optionally, ammonia tothe body of water 12 before determining the average rate of change intotal chlorine concentration and/or oxidation-reduction potential. Forinstance, the programming instructions can cause the controller 40 toengage (or control) a supply of chlorine, and optionally, ammonia andadd the chlorine, and optionally, ammonia to the body of water 12 whenit is determined that the residual chloramine concentration in a watersample is below a percentage selected within a range of 99% to 80% ofthe residual chloramine concentration set-point, or below a percentageselected within a range of 99% to 85% of the residual chloramineconcentration set-point, or below a percentage selected within a rangeof 99% to 90% of the residual chloramine concentration set-point, orbelow a percentage selected within a range of 99% to 95% of the residualchloramine concentration set-point.

In some preferred and non-limiting embodiments or aspects, thepreviously described method step of adding chlorine into the body ofwater 12 based on a chloramine concentration percentage is controlled bythe following algorithm: y<[(a)(x)]=add chlorine, where “y” is theresidual chloramine concentration determined in the first water sample,“a” is a percentage selected within a range of 99% to 80%, and “x” isthe residual chloramine concentration set-point. Further, the previouslydescribed method step of adding chlorine and ammonia into the body ofwater 12 based on a chloramine concentration percentage is controlled bythe following algorithm: y<[(a)(x)]=add chlorine and ammonia at a weightratio of chlorine to ammonia of greater than 5:1, where “y” is theresidual chloramine concentration determined in the first water sample,“a” is a percentage selected within a range of 99% to 80%, and “x” isthe residual chloramine concentration set-point. Thus, the programminginstructions can include, or can be modified to include, the abovealgorithm that, when satisfied, will cause the controller 40 toautomatically engage (or control) a supply of chlorine to add chlorineto the body of water 12.

It is appreciated that the predetermined chloramine concentration targetlevel used prior to determining the rate of change in total chlorineconcentration and/or oxidation-reduction potential can be based on atotal chlorine concentration target level. As such, the predeterminedchloramine concentration target level used in the previously describedmethod steps and algorithms and which is used before determining therate of change in total chlorine concentration and/oroxidation-reduction potential can be based on a predetermined totalchlorine concentration set-point or a percentage of the predeterminedtotal chlorine concentration set-point. In such embodiments, theresidual chloramine concentration is based on and/or determined from theresidual total chlorine concentration in the water samples.

In some preferred and non-limiting embodiments or aspects, chlorine andammonia are not added before determining the rate of change in totalchlorine concentration and/or oxidation-reduction potential. In suchembodiments, both chlorine and ammonia can be directly added afterdetermining that the desired set rate of change in total chlorineconcentration and the desired set rate of change oxidation-reductionpotential are not achieved.

As previously described, both chlorine and ammonia are added to the bodyof water 12 if the residual chloramine concentration is below thepredetermined chloramine concentration target level and the average rateof change in total chlorine concentration and/or oxidation-reductionpotential is below or above the set rate of change in total chlorineconcentration and/or oxidation-reduction potential such that the setrate of change in total chlorine concentration and/oroxidation-reduction potential is not achieved. Alternatively, if theresidual chloramine concentration is below the predetermined chloramineconcentration target level and the set rate of change in total chlorineconcentration and/or oxidation-reduction potential is achieved, thenchlorine and ammonia are not both added to the body of water 12.

In some preferred and non-limiting embodiments or aspects, whenchlorine, and optionally, ammonia being supplied to the body of water 12after determining that the residual chloramine concentration is belowthe predetermined chloramine concentration target level and the set rateof change in total chlorine concentration and/or oxidation-reductionpotential is achieved, the controller 40 can continue to supply chlorineonly to the body 12 or supply chlorine and ammonia at a weight ratio ofchlorine to ammonia of greater than 5:1. The method step of continuallyadding chlorine when the set rate of change in total chlorineconcentration and/or oxidation-reduction potential is achieved can becontrolled by the following example algorithms: (i) w≥y and w′<x=addchlorine, where “w” is the rate of change in total chlorineconcentration, “y” is the set rate of change in total chlorineconcentration, w′ is the residual chloramine concentration, and “x” isthe residual chloramine concentration set-point; or (ii) o≤p andw′<x=add chlorine, where “o” is the rate of change inoxidation-reduction potential, “p” is the set rate of change inoxidation-reduction potential, w′ is the residual chloramineconcentration, and “x” is the residual chloramine concentrationset-point. Thus, the programming instructions can include at least oneof the above algorithms that, when satisfied, will cause the controller40 to continue to automatically engage (or control) a supply of chlorineto add chlorine to the body of water 12.

Further, the method step of continually adding chlorine and ammonia at aweight ratio of chlorine to ammonia of greater than 5:1 when the setrate of change in total chlorine concentration and/oroxidation-reduction potential is achieved can be controlled by thefollowing example algorithms: (i) w≥y and w′<x=add chlorine and ammoniaat a weight ratio of chlorine to ammonia of greater than 5:1, where “w”is the rate of change in total chlorine concentration, “y” is the setrate of change in total chlorine concentration, w′ is the residualchloramine concentration, and “x” is the residual chloramineconcentration set-point; or (ii) o≤p and w′<x=add chlorine and ammoniaat a weight ratio of chlorine to ammonia of greater than 5:1, where “o”is the rate of change in oxidation-reduction potential, “p” is the setrate of change in oxidation-reduction potential, w′ is the residualchloramine concentration, and “x” is the residual chloramineconcentration set-point. Thus, the programming instructions can includeat least one of the above algorithms that, when satisfied, will causethe controller 40 to continue to automatically engage (or control) asupply of chlorine and ammonia to add chlorine and ammonia to the bodyof water 12 at a weight ratio of chlorine to ammonia of greater than5:1.

Further, if the residual chloramine concentration in a subsequentadditional water sample is determined to be at or above thepredetermined chloramine concentration target level, the programminginstructions will cause the controller 40 to stop the supply ofchlorine, and optionally, ammonia when also supplied, into the body ofwater 12.

In some preferred and non-limiting embodiments or aspects, the methodstep of stopping the supply of chlorine is controlled by the followingalgorithm: w≤x=stop the supply of chlorine, where “w” is the residualchloramine concentration determined in a water sample, and “x” is theresidual chloramine concentration set-point. Further, the method step ofstopping the supply of chlorine and ammonia when both supplied iscontrolled by the following algorithm: w≥x=stop the supply of chlorineand ammonia, where “w” is the residual chloramine concentrationdetermined in a water sample, and “x” is the residual chloramineconcentration set-point. Thus, the programming instructions can includethe above algorithm that, when satisfied, will cause the controller 40to stop automatically engaging (or controlling) a supply of chlorine andammonia, and therefore, stop adding chlorine and ammonia to the body ofwater 12.

In some preferred and non-limiting embodiments or aspects, differentprogramming algorithms are used to control when the supply of chlorine,and optionally ammonia when also supplied, into the body of water 12 isstopped. For instance, the method step of stopping the supply ofchlorine can be controlled by the following algorithm: w>[(t)(x)]=stopthe supply of chlorine, where “w” is the residual chloramineconcentration determined in the second water sample, “t” is a percentageselected within a range of 101% to 110%, and “x” is the residualchloramine concentration set-point. In addition, the method step ofstopping the supply of chlorine and ammonia can be controlled by thefollowing algorithm: w>[(t)(x)]=stop the supply of chlorine and ammonia,where “w” is the residual chloramine concentration determined in thesecond water sample, “t” is a percentage selected within a range of 101%to 110%, and “x” is the residual chloramine concentration set-point.

It is appreciated that the predetermined chloramine concentration targetlevel for stopping the addition of chlorine, and optionally ammonia whenalso supplied, can be based on a total chlorine concentration targetlevel. As such, the predetermined chloramine concentration target levelused in the previously described method steps and algorithms forstopping the addition of chlorine, and optionally ammonia when alsosupplied, can be based on a predetermined total chlorine concentrationset-point or a percentage of the predetermined total chlorineconcentration set-point. In such embodiments, the residual chloramineconcentration is based on and/or determined from the residual totalchlorine concentration in the water samples.

The method of the present invention works in accordance with thechloramine breakpoint curve, shown in FIG. 3. In particular, thepreviously described steps are used to achieve and maintain an idealstate of monochloramine disinfectant by predicting where the chloramineconcentration in the body of water 12 resides along the breakpointcurve, the rate at which chloramine concentration is increasing anddecreasing in the body of water 12 over time, and adjusting the input ofchlorine or chlorine and ammonia into the body of water 12 to achieveand maintain a position at or near the ideal state. As shown in FIG. 3,the ideal state (i.e., the maximum monochloramine concentrationobtainable in a body of water 12) is typically achieved at a weightratio of chlorine (Cl₂) to ammonia-nitrogen (NH₃−N) of 5:1.

Referring to FIGS. 4 and 5, and in one preferred and non-limitingembodiment or aspect, the method includes at least two modes, or stages,in view of the chloramine breakpoint curve. In the first mode shown inFIG. 4, it is assumed that free ammonia is present in the body of water12. During the first mode, water samples are periodically drawn from thebody of water 12 and analyzed to determine the chloramine concentration.In one preferred and non-limiting embodiment or aspect, thisdetermination is accomplished by measuring the total chlorine present inthe sample using a total chlorine analyzer, such as the total chlorineanalyzer commercially available from ProMinent Fluid Controls, Inc. ofPittsburgh, Pa. If the system 10 determines that the total chlorinelevels measured are in decline, the controller 40 can be configured toengage (or control) the treatment tubes 22 or 24 to add chlorine, andoptionally ammonia at a weight ratio of chlorine to ammonia of greaterthan 5:1, to the body of water 12. Newly added chlorine will react withthe free ammonia to generate chloramine, thus increasing theconcentration of chloramine in the body of water 12 and reducing theconcentration of free ammonia, as reflected in FIG. 4. Once the residualchloramine concentration target level is reestablished, or establishedin the first instance, the addition of chlorine, and optionally ammoniawhen also supplied, can cease.

In the second mode or stage of the control method as shown in FIG. 5, nofree ammonia is present in the body of water 12. Because no free ammoniais present, the addition of chlorine, and optionally ammonia at a weightratio of chlorine to ammonia of greater than 5:1, in response to arecognized drop in the chloramine concentration will result not in anupswing (or increase) in the chloramine concentration, as in the firstmode described above, but rather in a further reduction in thechloramine concentration. This is caused by the absence of a sufficientamount of free ammonia in the body of water 12, which precludes theformation of chloramine through a reaction between the added chlorineand free ammonia. If, after the addition of chlorine, and optionallyammonia at a weight ratio of chlorine to ammonia of greater than 5:1, inthe first mode, the chloramine concentration does not increase after asufficient amount of time and the rate of change in the totalconcentration concentration is below the set rate of change in totalchlorine concentration or the rate of change in the oxidation-reductionpotential is above the set rate of change in oxidation-reductionpotential, the system 10 can conclude that a sufficient amount of freeammonia is absent from the body of water 12. In response, the controller40 is configured to engage (or control) a source of chlorine and asource of ammonia to inject into the body of water 12 at a weight ratioof chlorine to ammonia of 5:1 or less, as reflected in FIG. 5. Theammonia and chlorine at a weight ratio of chlorine to ammonia of 5:1 orless can continue being added until analysis of water samples extractedfrom the body of water 12 determines that the residual chloramineconcentration target level has been reestablished (or established). Insome preferred and non-limiting embodiments or aspects, ammonia andchlorine are added at a weight ratio of chlorine to ammonia of 5:1 orless for a period a time and then stopped to allow for a lowconcentration of free ammonia without achieving the residual chloramineconcentration target level.

It is appreciated that the second mode is initiated by the ability ofthe system 10 to predict the location of the chloramine reaction on thebreak point curve and the rate at which the chloramine concentration isincreasing or decreasing. For instance, if the measured total chlorineresidual concentration continues to decrease as chlorine, and optionallyammonia at a weight ratio of chlorine to ammonia of greater than 5:1, isadded or if the oxidation-reduction potential continues to increase aschlorine, and optionally ammonia at a weight ratio of chlorine toammonia of greater than 5:1, is added, the system 10 can conclude that asufficient amount of free ammonia is not present and that the residualchloramine concentration is decreasing past the ideal state shown inFIG. 5. As a result, the second mode is initiated and the controller 40will add chlorine and ammonia into the body of water 12 at a weightratio of chlorine to ammonia of 5:1 or less.

In some preferred and non-limiting embodiments or aspects, the secondmode or stage of the control method is determined without engaging thesupply of chlorine, or chlorine and ammonia at a weight ratio ofchlorine to ammonia of greater than 5:1, when the total chlorine levelsmeasured are in decline, the rate of change in the total concentrationis below the set rate of change in total chlorine concentration, and therate of change in the oxidation-reduction potential is above the setrate of change in oxidation-reduction potential. In response, thecontroller 40 is configured to engage (or control) a source of chlorineand a source of ammonia to inject into the body of water 12 at a weightratio of chlorine to ammonia of 5:1 or less.

It is appreciated that the rate of change in total chlorineconcentration and/or oxidation-reduction potential can be used todetermine the chloramine concentration such as the concentration ofmonochloramine, di-chloramine, or the like. For instance, and aspreviously explained, the rate of change in total chlorine concentrationand/or oxidation-reduction potential can be used to determine if thechemicals in the body of water are in a state of monochloramine ordi-chloramine, which can then be used to determine chlorine and ammoniafeed rate and/or a ratio of chlorine to ammonia that should be suppliedto the body of water 12.

As indicated, any of the previously described method steps, orcombination of steps, can be used to establish, reestablish, andmaintain a desired residual chloramine level within the body of water12. In one preferred and non-limiting embodiment or aspect, at least oneof the previously described method steps, or combination of steps, areused to establish or reestablish a predetermined chloramineconcentration target level. After the desired predetermined chloramineconcentration target level is established or reestablished to complete afirst treatment cycle, a different algorithm can be used to reestablishthe desired residual chloramine concentration in subsequent treatmentcycles.

In one preferred and non-limiting embodiment or aspect, after a firsttreatment cycle is completed, the controller 40 is programmed to onlyengage (or control) a supply of chlorine and a supply of ammonia to addboth chlorine and ammonia to the body of water 12 at a weight ratio ofchlorine to ammonia of 5:1 or less in order to reestablish thepredetermined chloramine concentration target level. Thus, in suchembodiments, chlorine alone, or chlorine and ammonia at a weight ratioof chlorine to ammonia of greater than 5:1, is not added to the body ofwater 12 in a second treatment cycle. For example, after a firsttreatment cycle is completed, the programming instructions of thecomputer-readable storage mediums can be configured to cause thecontroller 40 to automatically add both chlorine and ammonia to the bodyof water 12 at a weight ratio of chlorine to ammonia of 5:1 or less whenthe residual chloramine concentration in a water sample is determined tobe below the predetermined chloramine concentration target level.

In some preferred and non-limiting embodiments or aspects, thepreviously described method step of adding ammonia and chlorine into thebody of water 12 in a second treatment cycle is controlled by thefollowing algorithm: y′<x′=add chlorine and ammonia at a weight ratio ofchlorine to ammonia of 5:1 or less, where “y′” is the residualchloramine concentration determined in a water sample of the secondtreatment cycle and “x′” is the residual chloramine concentrationset-point. Thus, the programming instructions can include the abovealgorithm for use in a second treatment cycle that, when satisfied, willcause the controller 40 to automatically engage (or control) a supply ofchlorine and a supply of ammonia to add both chlorine and ammonia to thebody of water 12 at a weight ratio of chlorine to ammonia of 5:1 orless.

The method can also use a chloramine concentration percentage of theresidual chloramine concentration set-point to determine when to addboth chlorine and ammonia to the body of water 12 at a weight ratio ofchlorine to ammonia of 5:1 or less in a second treatment cycle. Thechloramine concentration percentage can include, for example, apercentage selected within a range of 99% to 80% of the residualchloramine concentration set-point.

In some preferred and non-limiting embodiments or aspects, thepreviously described method step of adding chlorine and ammonia into thebody of water 12 at a weight ratio of chlorine to ammonia of 5:1 or lessin a second treatment cycle based on a chloramine concentrationpercentage is controlled by the following algorithm: y′<[(a′)(x′)]=addchlorine and ammonia at a weight ratio of chlorine to ammonia of 5:1 orless, where “y′” is the residual chloramine concentration determined ina water sample of the second treatment cycle, “a′” is a percentageselected within a range of 99% to 80%, and “x′” is the residualchloramine concentration set-point. Thus, the programming instructionscan include the above algorithm for use in a second treatment cyclethat, when satisfied, will cause the controller 40 to automaticallyengage (or control) a supply of chlorine and a supply of ammonia to addboth chlorine and ammonia to the body of water 12 at a weight ratio ofchlorine to ammonia of 5:1 or less.

Chlorine and ammonia are added to the body of water 12 until asubsequently obtained water sample is determined to be at or above theresidual chloramine concentration set-point or above a particularpercentage of the residual chloramine concentration set-point, at whichpoint the programming instructions will cause the controller 40 to stopthe supply of chlorine and ammonia into the body of water 12.

The predetermined chloramine concentration target level for addingchlorine and ammonia in a second or subsequent treatment cycle can bebased on a total chlorine concentration target level. In suchembodiments, the residual chloramine concentration is based on and/ordetermined from the residual total chlorine concentration in the watersamples.

After reestablishing the predetermined chloramine concentration targetlevel in the second treatment cycle, the programming instructions willcause the controller 40 to revert back to the original algorithm orcause the controller 40 to continue to use the modified algorithm. It isappreciated that the controller 40 can be programmed to alternatebetween different algorithms for any desired number of treatment cycles.For example, in a first treatment cycle, the controller 40 can beprogrammed to supply chlorine alone, or chlorine and ammonia at a weightratio of greater than 5:1, in a first step, and optionally, bothchlorine and ammonia at a weight ratio of chlorine to ammonia of 5:1 orless in a second step in order to establish the predetermined chloramineconcentration target level. Then, after a first treatment cycle iscompleted, the controller 40 can be programmed to supply both chlorineand ammonia only at a weight ratio of chlorine to ammonia of 5:1 or lessin order to reestablish the predetermined chloramine concentrationtarget level in the next three treatment cycles. Finally, to reestablishthe residual chloramine concentration set-point in a fifth treatmentcycle, the controller 40 can be programmed to use the original algorithmand supply chlorine alone, or chlorine and ammonia at a weight ratio ofgreater than 5:1, in a first step, and optionally, both chlorine andammonia at a weight ratio of chlorine to ammonia of 5:1 or less in asecond step.

The feed rate of chlorine and/or ammonia in any of the previouslydescribed steps can be determined from the reservoir 14 water volume anddwell time. As used herein, “dwell time” refers to the rate at whichwater volume changes in the reservoir 14. The feed rate of the chlorineand ammonia can also be controlled by the speed at which the meteringpumps distribute the chlorine and ammonia into the body of water 12. Forexample, the metering pumps can distribute chlorine and ammonia at amaximum speed rate. The metering pumps can also be reduced to half(i.e., 50%) of the maximum speed rate to adjust the feed rate ofchlorine and ammonia.

The method of automatically controlling chloramine concentrationdescribed herein allows for a desired amount of chloramine in a body ofwater 12 to be effectively maintained without directly measuring orinitially adding free ammonia. The system and method can also be used torespond to an adjustment, such as an increase, in the target chloramineconcentration.

FIGS. 6 and 7 show the total chlorine concentration, the rate of changein total chlorine concentration, the oxidation-reduction potential, andthe rate of change in oxidation-reduction potential in a water storagereservoir that utilized the treatment delivery system 10 and the methodof automatically controlling chloramine concentration according to thepresent invention. The treatment delivery system 10 was programmed toadd chlorine when the residual total chlorine concentration was belowthe predetermined total chlorine concentration target level. Further,while adding chlorine, the treatment delivery system 10 was alsoprogrammed to add chlorine and ammonia at a weight ratio of chlorine toammonia of 5:1 or less when the rate of change in the total chlorineconcentration is below the set rate of change in total chlorineconcentration or the rate of change in the oxidation-reduction potentialis above the set rate of change in oxidation-reduction potential.

As shown in FIG. 6, the system was turned on and hypochlorite was addedto the body of water 12 after determining that a water sample had aresidual total chlorine concentration below the predetermined totalchlorine concentration set-point. After adding the chlorine, the rate ofchange in total chlorine concentration and the rate of change inoxidation-reduction potential was calculated throughout the process.Referring to FIG. 7, the rate of change in residual total chlorineconcentration and the rate of change in oxidation-reduction potentialobtained over a specified period of time did not achieve the set rate ofchange in total chlorine concentration and the set rate of change inoxidation-reduction potential. As a result, and as shown in FIGS. 6 and7, the supply of ammonia was engaged along with the supply of chlorineat a weight ratio of chlorine to ammonia of 5:1 or less.

Moreover, the predetermined chloramine concentration target levelincluded a minimum predetermined total chlorine concentration set-pointand a maximum predetermined total chlorine concentration set-point. Oncethe minimum predetermined total chlorine concentration set-point wasreached, the feed rate of the chlorine and ammonia was decreased.Further, once the maximum predetermined total chlorine concentrationset-point was reached, the supply of chlorine and the ammonia into thebody of water 12 was stopped.

Whereas particular embodiments of this invention have been describedabove for purposes of illustration, it will be evident to those skilledin the art that numerous variations of the details of the presentinvention may be made without departing from the invention as defined inthe appended claims.

The invention claimed is:
 1. A method of automatically controlling chloramine concentration in a body of water contained in a reservoir, the method comprising: a) determining residual chloramine concentration in a water sample obtained from the body of water; b) determining at least one of the following when the residual chloramine concentration is below a predetermined target chloramine concentration level: i) an average rate of change in total chlorine concentration based on total chlorine concentrations of water samples obtained from the body of water; and ii) an average rate of change in oxidation-reduction potential based on oxidation-reduction potentials of water samples obtained from the body of water; and c) automatically engaging a supply of ammonia and a supply of chlorine to add both ammonia and chlorine to the body of water at a weight ratio of chlorine to ammonia of 5:1 or less when: i) the average rate of change in total chlorine concentration is below a set rate of change in total chlorine concentration; ii) the average rate of change in oxidation-reduction potential is above a set rate of change in oxidation-reduction potential; or iii) the average rate of change in total chlorine concentration is below a set rate of change in total chlorine concentration and the average rate of change in oxidation-reduction potential is above a set rate of change in oxidation-reduction potential.
 2. The method of claim 1, wherein the average rate of change in total chlorine concentration is determined in step b), and wherein ammonia and chlorine are both added to the body of water at a weight ratio of chlorine to ammonia of 5:1 or less in step c) when i) the average rate of change in total chlorine concentration is below the set rate of change in total chlorine concentration.
 3. The method of claim 1, wherein the average rate of change in oxidation-reduction potential is determined in step b), and wherein ammonia and chlorine are both added to the body of water at a weight ratio of chlorine to ammonia of 5:1 or less in step c) when ii) the average rate of change in oxidation-reduction potential is above the set rate of change in oxidation-reduction potential.
 4. The method of claim 1, wherein the average rate of change in total chlorine concentration and the average rate of change in oxidation-reduction potential is determined in step b), and wherein ammonia and chlorine are both added to the body of water at a weight ratio of chlorine to ammonia of 5:1 or less in step c) when iii) the average rate of change in total chlorine concentration is below the set rate of change in total chlorine concentration and the average rate of change in oxidation-reduction potential is above the set rate of change in oxidation-reduction potential.
 5. The method of claim 1, further comprising automatically engaging a supply of chlorine to add chlorine only to the body of water if the residual chloramine concentration in the water sample obtained from the body of water in step a) is below the predetermined target chloramine concentration level.
 6. The method claim 1, further comprising automatically engaging a supply of chlorine and a supply of ammonia to add both chlorine and ammonia to the body of water at a weight ratio of chlorine to ammonia of greater than 5:1 if the residual chloramine concentration in the water sample obtained from the body of water in step a) is below the predetermined target chloramine concentration level.
 7. The method of claim 6, wherein a feed rate of the chlorine and ammonia supplied to the body of water after step a) is different than a feed rate of the chlorine and ammonia supplied to the body of water in step c).
 8. The method of claim 4, wherein the average rate of change in total chlorine concentration and the average rate of change in oxidation-reduction potential in step b) is determined when the supply of chlorine and ammonia are disengaged.
 9. The method of claim 1, wherein the average rate of change in total chlorine concentration is determined by measuring the change in residual total chlorine concentration in consecutively obtained water samples over a fixed period of time, and wherein the average rate of change in oxidation-reduction potential is determined by measuring the change in oxidation-reduction potential in consecutively obtained water samples over a fixed period of time.
 10. The method of claim 1, wherein, if the average rate of change in total chlorine concentration is determined to be at or above the set rate of change in total chlorine concentration, chlorine only is added to the body of water or chlorine and ammonia are added to the body of water at a weight ratio of chlorine to ammonia of greater than 5:1.
 11. The method of claim 1, wherein, if the average rate of change in oxidation-reduction potential is determined to be at or below the set rate of change in oxidation-reduction potential, chlorine only is added to the body of water or chlorine and ammonia are added to the body of water at a weight ratio of chlorine to ammonia of greater than 5:1.
 12. The method of claim 1, wherein the supply of chlorine and the supply of ammonia are added to the body of water during step c) until a subsequently obtained water sample is determined to be at or above the predetermined target chloramine concentration level.
 13. The method of claim 12, wherein the predetermined target chloramine concentration level comprises a minimum predetermined total chlorine concentration set-point and a maximum predetermined total chlorine concentration set-point, and wherein the feed rate of the chlorine and/or the ammonia is decreased when the total chlorine concentration is at or above the minimum predetermined total chlorine concentration set-point and below the maximum predetermined total chlorine concentration set-point, and wherein the supply of chlorine and the supply of ammonia are disengaged when the total chlorine concentration is at or above the maximum predetermined total chlorine concentration set-point.
 14. The method of claim 1, wherein the feed rate of the chlorine and ammonia are determined by reservoir water volume and dwell time.
 15. The method of claim 1, wherein the residual chloramine concentration is based on a residual total chlorine concentration and the predetermined target chloramine concentration level is based on a target total chlorine concentration level.
 16. The method of claim 1, wherein the oxidation-reduction potentials of the samples are determined by measuring millivolts of the water samples.
 17. A treatment delivery system for automatically controlling chloramine concentration in a body of water contained in a reservoir comprising: a chemical dosing assembly; a water sampling assembly configured to extract water sample from the body of water at different points in time; one or more analyzers in fluid communication with the water sampling assembly and configured to determine at least total chlorine concentration, and optionally, oxidation-reduction potential in the water samples; a controller in operable communication with the one or more analyzers; and one or more computer-readable storage mediums in operable communication with the controller and containing programming instructions that, when executed, cause the controller to: a) determine residual chloramine concentration in a water sample obtained from the body of water; b) determine at least one of the following when the residual chloramine concentration is below a predetermined target chloramine concentration level: i) an average rate of change in total chlorine concentration based on residual total chlorine concentrations of water samples obtained from the body of water; and ii) an average rate of change in oxidation-reduction potential based on oxidation-reduction potentials of water samples obtained from the body of water; and c) automatically engage a supply of ammonia and a supply of chlorine to add both ammonia and chlorine to the body of water at a weight ratio of chlorine to ammonia of 5:1 or less when: i) the average rate of change in total chlorine concentration is below a set rate of change in total chlorine concentration while chlorine is added to the body of water; ii) the average rate of change in oxidation-reduction potential is above a set rate of change in oxidation-reduction potential while chlorine is added to the body of water; or iii) the average rate of change in total chlorine concentration is below a set rate of change in total chlorine concentration and the average rate of change in oxidation-reduction potential is above a set rate of change in oxidation-reduction potential.
 18. The system of claim 17, wherein the chemical dosing assembly is at least partially submerged in the body of water.
 19. The system of claim 17, wherein the computer-readable storage mediums in operable communication with the controller further comprise programming instructions that, when executed, cause the controller to automatically engage a supply of chlorine to add chlorine only to the body of water if the residual chloramine concentration in the water sample obtained from the body of water in step a) is below the predetermined target chloramine concentration level.
 20. The system of claim 17, wherein the computer-readable storage mediums in operable communication with the controller further comprise programming instructions that, when executed, cause the controller to automatically engage a supply of chlorine and a supply of ammonia to add both chlorine and ammonia to the body of water at a weight ratio of chlorine to ammonia of greater than 5:1 if the residual chloramine concentration in the water sample obtained from the body of water in step a) is below the predetermined target chloramine concentration level. 